Arthritis & Rheumatism, Volume 63,
November 2011 Abstract Supplement
Abstracts of the American College of
Rheumatology/Association of Rheumatology Health Professionals
Annual Scientific Meeting
Chicago, Illinois November 4-9, 2011.
Periostin, An Osteoblast Stimulating Factor, Regulates Cartilage Metabolism Via MMP-13 Activation.
Attur1, Mukundan, Palmer1, Glyn, Tachida2, Yuki, Kumakura2, Seiichiro, Shimada2, Kohei, Abramson1, Steven B.
Periostin (POSTN), a gamma-carboxylated extracellular matrix protein originally identified as an osteoblast stimulating factor. This study investigates its expression in OA cartilage and regulation of chondrocyte metabolism.
Cartilage slices were obtained from the advanced OA patients (age 4580 years) undergoing knee replacement surgery. Non-arthritic knee cartilages were obtained from autopsy patients within 24h (NDRI, Philadelphia). Predesigned TaqMan PCR primers were purchased from Applied Biosystems. Lentiviral shRNA targeting POSTN were purchased from Sigma. Matrix metalloproteinases proMMP-1 and proMMP-13 ELISA kits were from R&D Systems. Degradation products of type II collagen was measured using CTX II -based assay kit.
We studied the expression of POSTN in pools (n=10) of OA and age-matched non-diseased cartilage using U133 Affymetrix microarray. POSTN was overexpressed 24 fold in OA cartilage (p<0.035) compared to non-diseased controls. Verification by real-time PCR confirmed POSTN upregulation. Surgical-induction of OA in rats by anterior cruciate ligament transection (ACLT) and destabilization of the medial meniscus (DMM) models also significantly increased POSTN (311 fold) from 28 weeks after surgery. In OA chondrocytes isolated from human tibial cartilage, POSTN mRNA levels, determined by qPCR, were inhibited 3-fold in the presence of inflammatory cytokines IL-1b and TNFa. In contrast, TGFb-1 (2 ng/ml) significantly increased POSTN expression (240-fold). In functional assays, exogenously added (130 ug/ml) or overexpression of POSTN significantly increased MMP-13 expression and activity (p<0.02) in primary human OA, rat and bovine chondrocytes. Conversely; knock down of endogenous POSTN using targeted lentiviral shRNAs significantly decreased MMP-13 expression in the presence of TGF-b1. In OA cartilage explants cultures, PSTN increased cartilage degeneration, evidenced by increased release of collagen (C1, 2C) and GAG fragments in culture supernatants. To determine whether PSTN is a hypertrophic marker of chondrocytes we examined its expression in chondrogenesis assays using human bone marrow-derived MSCs and immature murine costal chondrocytes undergoing maturation. In both assays PSTN expression was upregulated in a time-dependent manner, and expression coincided with MMP-13, Alkaline Phosphatase and F-spondin. These findings suggest that PSTN expression is associated with chondrocyte terminal differentiation.
Together, these studies indicate that PSTN is a marker of OA cartilage and chondrocyte hypertrophy. In OA, PSTN may contribute to disease pathogenesis by promoting cartilage degradation via induction of MMP-13.
To cite this abstract, please use the following information:
Attur, Mukundan, Palmer, Glyn, Tachida, Yuki, Kumakura, Seiichiro, Shimada, Kohei, Abramson, Steven B.; Periostin, An Osteoblast Stimulating Factor, Regulates Cartilage Metabolism Via MMP-13 Activation. [abstract]. Arthritis Rheum 2011;63 Suppl 10 :1794